The present invention relates to a diaphragm type water inlet valve and, more particularly, to a diaphragm type water inlet valve suitable for use in an automatic electric washing machine.
The present invention relates to a pilot controlled pressure operated diaphragm type water inlet valve which operates by a pressure controlled by a pilot valve and, more particularly, to a pilot controlled pressure operated diaphragm type water inlet valve suitable for use in an automatic electric washing machine for mitigating a water hammering action.
It has conventionally been proposed to provide a pilot controlled pressure operated diaphragm type water inlet valve of the type which operates by a pressure controlled by a pilot valve provided by a plunger of an electro-magnetic solenoid.
A pilot controlled pressure operated diaphragm type water inlet valve described in, for example, U.S. Pat. No. 3,672,627, wherein the valve includes a diaphragm valve member adapted to be seated on an annular valve seat, an external peripheral bellows portion, and a central orifice which is opened and closed by a pilot valve. Additionally, a communicating extraction hole having a cross-sectional area which is smaller than that of the central orifice is formed in another member of the diaphragm valve member.
In order to prevent the cross-sectional areas of the central orifice and the communicating extraction hole from varying due to the deformation, corrosion or the like, a synthetic resin-made inserted element member is provided in a center of the diaphragm valve having the central orifice and the communicating extraction hole which is located at a position radially remote from the central orifice.
It has been proposed that at a downstream portion of the diaphragm valve, a guiding rib member and a columnar portion member, which is adapted to rapidly reduce the flow passage area of the water when the diaphragm valve opening is reduced, are provided. The movement of the diaphragm valve is guided by the guiding rib member and the columnar portion member during operation and the water hammering action is mitigated by decreasing the velocity of the water flow immediately before the diaphragm valve is fully opened.
The above described conventional pilot controlled pressure operated diaphragm type water inlet valve has a number of disadvantages such as, for example, an influence of the deformation resulting from a small gap between the guiding rib member and the inner periphery portion of the flow passage, and the clogging by the foreign matter in a gap between the columnar portion member and the inner periphery portion of the flow passage due to a rapid reduction in the flow passage area.
As a result, the conventional pilot controlled pressure operated diaphragm type water inlet valves occasionally malfunction have a complicated structure, and also have an inferior reliability.